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      1 /*
      2  * Copyright (C) 2009 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 package android.graphics.utils;
     18 
     19 import android.graphics.Bitmap;
     20 import android.graphics.BitmapShader;
     21 import android.graphics.Canvas;
     22 import android.graphics.Paint;
     23 import android.graphics.Shader;
     24 import android.graphics.Xfermode;
     25 
     26 /**
     27  * @hide
     28  */
     29 public class BoundaryPatch {
     30     private Paint   mPaint;
     31     private Bitmap  mTexture;
     32     private int     mRows;
     33     private int     mCols;
     34     private float[] mCubicPoints;
     35     private boolean mDirty;
     36     // these are the computed output of the native code
     37     private float[] mVerts;
     38     private short[] mIndices;
     39 
     40     public BoundaryPatch() {
     41         mRows = mCols = 2;  // default minimum
     42         mCubicPoints = new float[24];
     43         mPaint = new Paint();
     44         mPaint.setDither(true);
     45         mPaint.setFilterBitmap(true);
     46         mDirty = true;
     47     }
     48 
     49     /**
     50      * Set the boundary to be 4 cubics. This takes a single array of floats,
     51      * and picks up the 12 pairs starting at offset, and treats them as
     52      * the x,y coordinates of the cubic control points. The points wrap around
     53      * a patch, as follows. For documentation purposes, pts[i] will mean the
     54      * x,y pair of floats, as if pts[] were an array of "points".
     55      *
     56      * Top: pts[0..3]
     57      * Right: pts[3..6]
     58      * Bottom: pts[6..9]
     59      * Right: pts[9..11], pts[0]
     60      *
     61      * The coordinates are copied from the input array, so subsequent changes
     62      * to pts[] will not be reflected in the boundary.
     63      *
     64      * @param pts The src array of x,y pairs for the boundary cubics
     65      * @param offset The index into pts of the first pair
     66      * @param rows The number of points across to approximate the boundary.
     67      *             Must be >= 2, though very large values may slow down drawing
     68      * @param cols The number of points down to approximate the boundary.
     69      *             Must be >= 2, though very large values may slow down drawing
     70      */
     71     public void setCubicBoundary(float[] pts, int offset, int rows, int cols) {
     72         if (rows < 2 || cols < 2) {
     73             throw new RuntimeException("rows and cols must be >= 2");
     74         }
     75         System.arraycopy(pts, offset, mCubicPoints, 0, 24);
     76         if (mRows != rows || mCols != cols) {
     77             mRows = rows;
     78             mCols = cols;
     79         }
     80         mDirty = true;
     81     }
     82 
     83     /**
     84      * Reference a bitmap texture to be mapped onto the patch.
     85      */
     86     public void setTexture(Bitmap texture) {
     87         if (mTexture != texture) {
     88             if (mTexture == null ||
     89                     mTexture.getWidth() != texture.getWidth() ||
     90                     mTexture.getHeight() != texture.getHeight()) {
     91                 // need to recompute texture coordinates
     92                 mDirty = true;
     93             }
     94             mTexture = texture;
     95             mPaint.setShader(new BitmapShader(texture,
     96                                               Shader.TileMode.CLAMP,
     97                                               Shader.TileMode.CLAMP));
     98         }
     99     }
    100 
    101     /**
    102      * Return the paint flags for the patch
    103      */
    104     public int getPaintFlags() {
    105         return mPaint.getFlags();
    106     }
    107 
    108     /**
    109      * Set the paint flags for the patch
    110      */
    111     public void setPaintFlags(int flags) {
    112         mPaint.setFlags(flags);
    113     }
    114 
    115     /**
    116      * Set the xfermode for the patch
    117      */
    118     public void setXfermode(Xfermode mode) {
    119         mPaint.setXfermode(mode);
    120     }
    121 
    122     /**
    123      * Set the alpha for the patch
    124      */
    125     public void setAlpha(int alpha) {
    126         mPaint.setAlpha(alpha);
    127     }
    128 
    129     /**
    130      * Draw the patch onto the canvas.
    131      *
    132      * setCubicBoundary() and setTexture() must be called before drawing.
    133      */
    134     public void draw(Canvas canvas) {
    135         if (mDirty) {
    136             buildCache();
    137             mDirty = false;
    138         }
    139 
    140         // cut the count in half, since mVerts.length is really the length of
    141         // the verts[] and tex[] arrays combined
    142         // (tex[] are stored after verts[])
    143         int vertCount = mVerts.length >> 1;
    144         canvas.drawVertices(Canvas.VertexMode.TRIANGLES, vertCount,
    145                             mVerts, 0, mVerts, vertCount, null, 0,
    146                             mIndices, 0, mIndices.length,
    147                             mPaint);
    148     }
    149 
    150     private void buildCache() {
    151         // we need mRows * mCols points, for verts and another set for textures
    152         // so *2 for going from points -> floats, and *2 for verts and textures
    153         int vertCount = mRows * mCols * 4;
    154         if (mVerts == null || mVerts.length != vertCount) {
    155             mVerts = new float[vertCount];
    156         }
    157 
    158         int indexCount = (mRows - 1) * (mCols - 1) * 6;
    159         if (mIndices == null || mIndices.length != indexCount) {
    160             mIndices = new short[indexCount];
    161         }
    162 
    163         nativeComputeCubicPatch(mCubicPoints,
    164                                 mTexture.getWidth(), mTexture.getHeight(),
    165                                 mRows, mCols, mVerts, mIndices);
    166     }
    167 
    168     private static native
    169     void nativeComputeCubicPatch(float[] cubicPoints,
    170                                  int texW, int texH, int rows, int cols,
    171                                  float[] verts, short[] indices);
    172 }
    173 
    174